Skip to main content

Full text of "Text Book Of Mechanical Engineering"

See other formats


820

Appendix II.

I:

IR !

i I 1

*

P. 256. Turning Balls.—Brass and gun-metal balls are
much used for feed-pump- and safety-valves on account of
absence of sticking which they ensure. To turn them in the
lathe, a cup.chuck in hard wood—A, Fig. 790—is provided, into-

which the ball is fixed. This form of chuck permits the work
to be constantly changed in position; and, if this be carefully
done, it will be clear that any section will be a circle, which is